Source code for airflow.hooks.base
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"""Base class for all hooks"""
import logging
import warnings
from typing import TYPE_CHECKING, Any, Dict, List
from airflow.typing_compat import Protocol
from airflow.utils.log.logging_mixin import LoggingMixin
if TYPE_CHECKING:
from airflow.models.connection import Connection # Avoid circular imports.
[docs]log = logging.getLogger(__name__)
[docs]class BaseHook(LoggingMixin):
"""
Abstract base class for hooks, hooks are meant as an interface to
interact with external systems. MySqlHook, HiveHook, PigHook return
object that can handle the connection and interaction to specific
instances of these systems, and expose consistent methods to interact
with them.
"""
@classmethod
[docs] def get_connections(cls, conn_id: str) -> List["Connection"]:
"""
Get all connections as an iterable, given the connection id.
:param conn_id: connection id
:return: array of connections
"""
warnings.warn(
"`BaseHook.get_connections` method will be deprecated in the future."
"Please use `BaseHook.get_connection` instead.",
PendingDeprecationWarning,
stacklevel=2,
)
return [cls.get_connection(conn_id)]
@classmethod
[docs] def get_connection(cls, conn_id: str) -> "Connection":
"""
Get connection, given connection id.
:param conn_id: connection id
:return: connection
"""
from airflow.models.connection import Connection
conn = Connection.get_connection_from_secrets(conn_id)
log.info("Using connection ID '%s' for task execution.", conn.conn_id)
return conn
@classmethod
[docs] def get_hook(cls, conn_id: str) -> "BaseHook":
"""
Returns default hook for this connection id.
:param conn_id: connection id
:return: default hook for this connection
"""
# TODO: set method return type to BaseHook class when on 3.7+.
# See https://stackoverflow.com/a/33533514/3066428
connection = cls.get_connection(conn_id)
return connection.get_hook()
[docs] def get_conn(self) -> Any:
"""Returns connection for the hook."""
raise NotImplementedError()
@classmethod
@classmethod
[docs] def get_ui_field_behaviour(cls) -> Dict[str, Any]:
...
[docs]class DiscoverableHook(Protocol):
"""
Interface that providers *can* implement to be discovered by ProvidersManager.
It is not used by any of the Hooks, but simply methods and class fields described here are
implemented by those Hooks. Each method is optional -- only implement the ones you need.
The conn_name_attr, default_conn_name, conn_type should be implemented by those
Hooks that want to be automatically mapped from the connection_type -> Hook when get_hook method
is called with connection_type.
Additionally hook_name should be set when you want the hook to have a custom name in the UI selection
Name. If not specified, conn_name will be used.
The "get_ui_field_behaviour" and "get_connection_form_widgets" are optional - override them if you want
to customize the Connection Form screen. You can add extra widgets to parse your extra fields via the
get_connection_form_widgets method as well as hide or relabel the fields or pre-fill
them with placeholders via get_ui_field_behaviour method.
Note that the "get_ui_field_behaviour" and "get_connection_form_widgets" need to be set by each class
in the class hierarchy in order to apply widget customizations.
For example, even if you want to use the fields from your parent class, you must explicitly
have a method on *your* class:
.. code-block:: python
@classmethod
def get_ui_field_behaviour(cls):
return super().get_ui_field_behaviour()
You also need to add the Hook class name to list 'hook_class_names' in provider.yaml in case you
build an internal provider or to return it in dictionary returned by provider_info entrypoint in the
package you prepare.
You can see some examples in airflow/providers/jdbc/hooks/jdbc.py.
"""
@staticmethod
@staticmethod
[docs] def get_ui_field_behaviour() -> Dict[str, Any]:
"""
Returns dictionary describing customizations to implement in javascript handling the
connection form. Should be compliant with airflow/customized_form_field_behaviours.schema.json'
If you change conn_type in a derived class, you should also
implement this method and return field customizations appropriate to your Hook. This
is because the child hook will have usually different conn_type and the customizations
are per connection type.
.. seealso::
:class:`~airflow.providers.google.cloud.hooks.compute_ssh.ComputeSSH` as an example
"""
...
